Powder coating technology involves applying a coating of a thermoplastic or thermoset powder, for example a polyamide, polyester, polyolefin, urethane, acrylic, fluoropolymer or epoxy system, to a substrate and forming a continuous film through coalescence of the powder particles at temperatures greater than the powder melting point. In the case of thermoset chemistries, the powder is also cured/polymerized during the coalescence phase. Generally curing/polymerization of thermoset powders is initiated thermally or by exposure to radiation, e.g., with ultraviolet (UV) light.
In some cases, it is desirable to apply a surface texture to the coating, such that the cured coating will be textured. U.S. Pat. No. 6,238,750 discloses techniques that are said to impart smoothness or texture to a powder coated surface by compressing the surface with a “flexible confining membrane” or “an engraved or etched photolithographic pattern on the pressing surface.” Some commercial processes impart a crude texture to powdered coatings by manipulating the coating formulation, for example by using powders having various particle sizes and melting temperatures in the powder coating formulation.